Load XML through Https

Hi there, well i am attempting to make a konfabulator widget which will download the current download usage from my ISP. konfabulator script language is javascript, so i am restrained slightly by that.

The ISP has an xml feed with the variables i need, its on an https though, and im unsure what kind of script to use at access a https. I have been fiddling around with XMLHttpRequest() but cant seem to get that to work with a username and password.
Any insight from anyone else about a way to get it to work would be great.